Process for refining a soap base



June 18, 1935. J. wl BODMAN PROCESS FOR REFINING A SOAP BASE Filed June24, 1930 2 Sheets-Sheet l June 18, 1935. J, w. BODMAN PROCESS FORREFINING A soar BASE Filed June 24, 1930 2 Shuts-Sheet 2 a (New. A

i'vr NW Patented June. 18, 1935 U IT D STATES totem.PBQCISSI'OBWQASOAPBASI Application Jul-e24, 1m. No. 403,414

4 Claims. (CI. 87-16) The present invention relates generally to aprocessforrefiningasoapbase, andmorespeeifically to a process forconverting a partiallydried soap base which may have a varying moisiture content and partially crystalline structure into a homogeneous,plastic mass from which bars or cakes may be produced by conventionalmethods while simultaneously afiording an effective method for theuniform incorporation of perfuming, filling, and such other ingredientsas may be soap. 'Ihe purpose of the invention is to provide an improvedand simplified method for working a heterogeneous, partially-driedsoapbase in the form of chips, spray-dried particles or granules into ahomogeneous mass having the desired physical properties for extrusion,or similar or equivalent shaping operations, into bars from which cakesof soap can be molded and stamped.Arelatedpurposeistouniformlyincorporate within thesoap base during theprocess ofconversion other commonly used ingredients," such as perfumein the case of toilet soap anddyes or pigments where color is desired.

Still another purpose of the invention is to remove and exclude from therefined base any coarse foreign material which may inadvertently havebeen picked up inthe course of mechanicallyliandling the stockfrom thesoapery through the dryers, and to eliminate by assimilation into I thehomogeneous mass occasional small lumps of hard, over-dried soap.

Due to the severalrelated functions which it performs, the presentprocess can be considered and generally defined as a process forrefining a soap base. in which the mechanical operations of mixing,levigating, and plasticizing are simultaneously performed in arelatively'simple and efiicient manner.

The present process has particular application in the manufacture oftoilet soap from dried stock, such as chips, air-dried particles orgranules. Soap as it comes from the kettle following the operations of"settling" will contain approximately thirty per cent. moisture. In thisform it may be drawn on into frames" where on cooling it solidifiessuificiently for cutting into bars. But-for the finer. grades of toiletsoap it is necessary to remove some of the water before forming intobars. This can be accomplished in a variety of ways, the mostconventional of which is to fiow the molten kettle soap'over coolingrolls from which it is scraped oil. in sheets or ribbonspnto a beltmoving through a drying chamber in which a r tillatedcirculation ofdrying air is maintained. The resultant partiallydried sheets or ribbonsof soap which have, assumed a friable condition occasioned by the lossofmoistureare broken up into chips by necessary or desirable in thefinished further handling in mechanical conveyors. Although such amethod'of drying is rapid and economical. removing thirty-five per cent.or more of the associated water from the kettle soap, it .is practicallyimpossible to secure uniform drying throughout the mass, and inconsequence a certain small but significant portion of the soap may evenbe dried to a point where it does not readily reabsorb moisture onstanding in contact or while worked with soap of substantially highermoisture content. If particles of such over-dried soap are notre-hydrated or uniformly dispersed as particles of infinitesimal size, abar of soap made from such unrefined stock is obiectionably gritty as itwears away in use.

In commercial practice, the levigation of partially-dried kettle soap isuniversally carried out by passing the partially-dried soap base throughmilling apparatus, consisting of a series of .rolls of progressivelyincreasing circumferential speed and decreasing clearance betweensuccessive pairs of mils. This milling operation is also employed tocombine other ingredients. such .as perfume, which is generally added tothe chips or mill feed in other form to secure a preliminary roughdistribution. The passage of the soap base between the bite ofsuccessive pairs'of rolls is intended to break down the larger physicalaggregateaand reduce the soap to as nearly a plastic condition aspossible. The

milled soap scraped from the last roll in the a series, which maycomprise eight, ten or more pairs of rolls in all, is in the form .ofthin ribbons quite bulky in the mass. The following mechanical operationis intended to compress the ribbons into a continuous bar of desireddimensions fromwhich inividual cakes maybe cut. The machine commonlyemployed for this operation is known as a plodder, and comprises acontinuous screw revolving in a horizontal chamber of circularcross-section, provided on the discharge endwith a conical section fromwhich the bar is continuously discharged.

While it is possible to manufacture an ac-- ceptable bar of toflet soapby the milling method commonly employed and briefly described above,nevertheless this method of refining has many important andcharacteristic disadvantages long recognized by those skilled in theart. It utterly fails to screen and exclude coarse foreign materialsfrom the-soap base. It is inadequate to produce a quality of uniformitymuch desired, and lacks the control necessary to invariably produce andreproduce a refined soap having the desirable homogeneous structure.Furthermore, the milling apparatus is costlyto install, requiresexcessive floor space in proportion to its unit of capacity, andexcessive power for its operation. Inasmuch as the physical propertiesof a milled soap are improved'by continued working with lessenedclearance between the milling rolls, the improvement in this type ofsoap necessitates still further milling rolls with a greater powerconsumption without, however, producing a proportionate im provement inthe quality of the material.

According to the present invention, the soap base is completely refinedafter the addition of the final ingredients in such a manner as tocompletely plasticize and homogenize the stock, and cause uniformdistribution or dispersion of perfuming, filling, and other addedingredients throughout the mass. This is preferably accomplished byforcing the soap while maintained in a plastic condition through aseries of minute orifices under comparatively high pressure. Theextrusion of the soap through these orifices thoroughly extends andworks the mass, and the shearing action which takes place in plasticfiow is extremely effective in producing a product having the desiredphysical properties. This is apparently due to the fact that themechanical working of the soap is attributable to the linear fiow of thestock forced under pressure through the orifices, with concentric layersflowing at different relative speeds with attendant shearing and millingaction. For the purpose of promoting the most economical operation, itis preferable to initially force or extrude the soap stock throughorifices larger than the final orifices, and thereafter as the fiuidityof the soap stock increases from stage to stage to progressivelydecrease the orifices until the final size of orifice is reached. Forthe further promotion of greatest efficiency, it is desirable tothermostatically control the temperature conditioning of the soap duringthe refining process, or in other words to insure that the soap shall bemaintained during its extrusion through the minute orifices at atemperature best adapted to maintain the desired flow conditions. Thistemperature should neither be so high as to cause too great fiuidity ofthe soap nor so low as to cause the soap to harden and interfere withits proper handling during the process of refining.

It has been found that the efficiency of the operation can best bemaintained through the provision of orifices, such as those furnished bya fine mesh screen surface. To maintain the screen against theconsiderable pressure engendered by the forcing of the soap basetherethrough, it is desirable to back the screen with a support designedto permit the passage of the extruded soap freely therethrough. Therefining action secured by the employment of minute orifices ofinconsiderable depth is much superior to the action produced by forcingthe soap through orificial passages of considerable depth, as in thecase of a perforated plate of sufilcient thickness to withstand thepressures engendered in forcing the soap therethrough. It is proposed todeliver the soap stock to the orificial surfaces, as screens, by screwsoperating in closed barrels, which are designed to primarily compact andbring the mass as a whole to an optimum temperature controlled throughthe employment of a surrounding jacket which in the present case mayhave water circulating therein to control the upper limit of temperatureand avoid undue elevation in temperature of the soap. To promote thevolumetric efficiency of the orificial surfaces and aid in reducing hardparticles by attrition, one or more revolving blades may be mounted onthe screw shaft and serve by rotating in proximity to the orificialsurface to aid in working the plastic mass of soap thercthrough, furtherreducing by attrition hard particles of dried soap which may be presentinto such a condition that these particles are completely assimilated bythe mass. Not only does the homogenizing of the soap coupled with theprior conditioning effectually refine the plastic material, especiallywhen repeated through orifices of diminishing size, but the extrusion orforcing of the soap through the minute orifices serves a screeningfunction to preclude conveyance into the finished soap of such foreignmaterials as may inadvertently be collected and which cannot be reducedby the condition ing of the material.

An important and desirable aspect of the process is the maintenance ofthe soap base during the refining thereof at a predetermined consistencythrough the maintenance of temperature between generally predeterminedlimits. By properly controlling the consistency through maintenance oftemperature in this manner, the desired refining results may be secured,whereas without such maintenance of proper temperature conditions,attempts to thus refine the soap are ineffective. It follows, therefore,that the development of the refining operation in a closed system withthe maintenance of predetermined temperature limits is an important andessential adjunct of the process.

According to the best method of practising the invention now known, theplasticized soap is forced through and extruded from wire screens whichprogressively diminish in size of mesh. Goods results have been obtainedby graduating the mesh from an initial screening area of twenty meshdownwardly to forty mesh, with possibly one intermediate screentherebetween. In conjunction with the wire screening devices, it hasbeen found desirable, as stated heretofore, to provide perforatedsupports to resist the pres-t sure on the screens, but provided howeverwith relatively large openings, the aggregate area of whichsubstantially exceeds that of the screen openings, thus avoiding anyrestriction from the passage of the homogenized soap therethrough.

In the accompanying drawings illustrating the preferred form of theinvention,

Fig. 1 represents an elevation partly in section of a suitable apparatusfor carrying out my process; and

Fig. 2 is a section illustrating the screen and correlated devices on anenlarged scale.

As carried out in this apparatus, a kettle soap dried to a moisturecontent of five to twenty per cent. approximately, and to which hasalready been added perfuming, filling, and such other ingredients as aredesirable, is delivered to a hopper l communicating with the interior ofa closed chamber or barrel l2 in which is mounted a revolving feed screwI 4. This feed screw conveys the soap lengthwise of the barrel, andpreliminarily plasticizes and mixes it during its travel. At thedelivery end of the feed screw is located the initial screen l6 oftwenty mesh approximately, supported by a plate I8. Operating inconjunction with the screen and in proximity thereto are a series ofrotating blades 20 mounted upon the shaft 2| of the feed screw,

and aiding to force the plasticized stock through the screening device.The blades effectively augment the function of the feed screw by virtueof the attritive effect exerted upon the soap, tending to reduce hardparticles of soap to dimensions of sufficient size to permit their readypassage through the screen. The feeding device coupled with theresistance at the surface of the screen creates a substantial pressuregenerally in excess of 250 pounds per square inch which is instrumentalin creating the desired action upon the soap. From the first or initialscreen of twenty mesh, the partially refined soap is discharged throughthe duct 24 to a second or intermediate feed screw 26 which delivers thesoap to a second or intermediate screen 28 of thirty mesh, this screenbeing supported by a perforated member 30 and cooperating with attritiveblades 32 in a manner similar to that previously described. From thissecond or intermediate screen, the soap is again discharged through a.duct 36 to a feed screw 38 which conveys it to a third and final screeniii of forty mesh, having a perforated support 42 and cooperating withblades Obviously the number and character of screening devices may wellbe altered as occasion requires without affecting the broad concept ofmy invention. Furthermore, the size of the screens may be altered as thecondition of the base may necessitate. The soap base in process ofrefining is maintained within desired temperature limits through theemployment of a surrounding jacket adapted to contain temperatureregulating fluid, such as steam or water, depending upon whether thefunction is to remove the heat from the mass of soap or prevent escapeof heat therefrom. This jacket, as indicated generally at 50, surroundseach of the plasticizing chambers or barrels. If extreme accuracy isdesired, the requisite temperatures within the refining apparatus may bemaintained by any desired method of temperature control (not shown), orin the absence of such method of temperature control, approximatetemperature limits can be maintained satisfactorily by manual control ofthe volume and temperature of the fluid passing through the jackets. Theoptimum temperature at which the base should be worked cannot bespecified precisely and is governed by the characteristics of theparticular soap stock in process of refining. Generally speaking, thecondition of the soap should be such as to maintain a substantialworking pressure at the orificial surfaces.

A specific example of the improved method of refining may be cited inconnection with a kettle soap having the following composition:

Per cent Palm oil 50 Tallow 25 Cocoanut oil 25 The soap coming from thekettle contains approximately thirty per cent. of moisture, and ispartially dried in chip form to a twelve per cent. moisture contentapproximately. These partially dried chips are delivered to the firststage of the refining operation at a temperature slightly above F. Thistemperature may rise slightly throughout the three stages of theoperation, approximately 10 to 20 higher at the completion of therefining operation. It will be understood that the entering temperatureis determined by practical operating conditions, and might desirably besomewhat lower than that indicated without in any way altering and infact in some cases improving the efiiciency of the operation.

As will be evident to those skilled in the art in view of the foregoingspecification, my improved process as carried out in the above-describedapparatus accomplishes several distinct and advantageous results.nlpulation of the soap on passage through the screening devices,especially when complemented by the attrition of the stock in proximityto the screening devices, thoroughly homogenizes all of the soapsubjected to the refining operation, repeatedly extruding it incondition particularly favorable for compression into a smooth bar. Thehard particles of soap are progressively reduced by attrition, and theaccompanying hydration until. they are completely absorbed in the soapas a whole. Aside from the major and important function of thoroughlyworking and homogenizing the soap, the screens serve the further anduseful purpose of impeding or preventing the passage of foreign materialwhich may inadvertently collect in the soap and which is of such acharacter that it cannot be reduced and caused to pass therethrough.Obviously this foreign material collects ahead of the screens, isremoved from the soap passing therethrough, and can be completelyremoved from the refining apparatus by removal and cleaning of thescreens.

What is claimed is:

1. That step in the process of homogenizing and refining a soap base forthe production of a homogeneous plastic mass from which bars or cakesmay be subsequently formed, which consists in regulating the temperatureof the base to maintain a predetermined condition of plasticity and,while so maintained, forcing the base under high pressure through minuteorifices of a size comparable to or less than the orifices of a 20-meshscreen.

2. The process of homogenizing and refining a soap base for theproduction of a homogeneous plastic mass from which bars or cakes may besubsequently formed, which consists in regulating the temperature of thebase to maintain a predetermined condition of plasticity and, while somaintained, repeatedly forcing the base under a high pressure throughsuccessive sets of minute orifices of decreasing size, with none of theorifices having a. size comparably greater than the openings of a20-mesh screen.

3. In the process of homogenizing and refining a soap base for theproduction of a homogeneous plastic mass from which bars or cakes may besubsequently formed, the steps which consist in regulating thetemperature of the base to maintain a predetermined condition ofplasticity and, while so maintained, forcing the base under highpressure through minute orifices of a size comparable to or less thanthe openings of a 20-mesh screen and supplementing the forcing bypressure through the orifices by a rubbing and attritive action.

4. That step in the process of homogenizing and refining a soap basehaving a moisture content not in excess of 25% approximately for theproduction of a homogeneous plastic mass from which bars or cakes may besubsequently formed, which consists in regulating the temperature of thebase to maintain a predetermined condition of plasticity and, while somaintained, forcing the base under high pressure through minute orificesof a size comparable to or less than that of the openings in a 20-meshscreen.

JOHN W. BODMAN.

The working or ma-

